Dual Thermal Switch Control for Heating Device Reset Safety

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Solution Overview

Problem

Conventional safety capillary tube thermostats in heat pumps are sensitive to low ambient temperatures, leading to unintended tripping during storage or transport, which can result in unnoticed failures and safety issues due to their non-self-resettable nature, limiting their reliability and safety in auxiliary heating systems.

Innovation Solution

A dual-switching device system comprising a non-self-resettable and an automatically resettable switching device, where the automatically resettable device triggers at a lower temperature than the non-self-resettable one, allowing controlled reconnection to the electrical supply voltage after fault analysis, enhancing safety and reliability by preventing accidental reactivation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If an automatically resettable switching device is used, then ease of operation is improved by automatic reset after tripping, but safety deteriorates due to potential unintended reactivation without fault analysis

Engineering Contradiction:
Improveautomatic resetVSAvoidsafety
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The safety system is segmented into two distinct switching devices with different reset behaviors. The automatically resettable switching device provides ease of operation through automatic reset, while the non-self-resettable switching device maintains safety by requiring manual intervention. This segmentation allows each device to fulfill its specific function without compromising the other's advantages.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The non-self-resettable switching device is designed to trip at a lower temperature threshold than the automatically resettable device. This preliminary action ensures that when a genuine overheating fault occurs, the non-self-resettable device trips first, manually preventing reactivation until the fault is addressed. The automatically resettable device then provides automatic reset capability for minor fluctuations, combining both safety and ease of operation.

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution increases safety and reliability by ensuring that heating elements are only reconnected to the electrical supply voltage after a deliberate reset, preventing unintended reactivation and improving compliance with safety standards, thus reducing the likelihood of unnoticed failures.

Implementation Method 1

a non-self-resettable switching device (10) with a first defined triggering temperature T1 and an automatically resettable switching device (20) with a triggering temperature T2

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

switching devices (10, 20), with which all heating elements (201, 202) of the heating device (200) can be switched to the electrical supply voltage L, N

Methodology Applied
Scientific EffectBimetallic strip: Bi-Metallic Strip

Data Source

PatentEP4050969A1Device and method for operating a heating device
Publication Date: 2022.08.31 ROBERT BOSCH GMBH
  • EP4050969A1 patent drawingFigure 1
  • EP4050969A1 patent drawingFigure 2~3
  • EP4050969A1 patent drawing

AI summary

Device (100) for operating a heating device (200), comprising a non-self-resetting switching device (10) with a first defined tripping temperature (T1) and an automatically resettable switching device (20) with a second defined tripping temperature (T2); wherein the tripping temperature (T2) of the automatically resettable switching device (20) is defined as lower than the tripping temperature (T1) of the non-self-resettable switching device (10), wherein the switching devices (10, 20) are connected to a control device (30), wherein the device (100) is configured such that the heating device (200) can be switched to an electrical supply voltage (L, N) by means of a reset device (5) connected to the control device (30) due to a tripping of at least the automatically resettable switching device (20).